Apparatus for closing and interrupting an electric circuit



March 29, 1932. 1 F. G, 'R HARTMANN 1,851,704

APPARATUS FCR CLOSING AND INTERRUPTING AN ELECTRIC` CIRCUIT Zz Ea/Ei U 2E fl. l,

50 E 2f-E l March 29, 1932- .1. F. G. P. HARTMANN APPARATUS FOR CLOSINGAND INTERRUPTING AN ELECTRIC CIRCUIT Filed July l2, 1928 5 SheetS-Sheeb2 March 29, 1932. J, F. G. P. HARTMANN 1,851,704

APPARATUS FO CLOSING AND INTERRUPTING AN ELECTRIC CIRCUIT Filed July 12,1928 3 Sheets-Sheet 5 Mmm Patented Mar. 29, 1932 UNITED STATE P'I'EN'IDOFFICE APPARATUS FOR CLOSING .AND INTERRUPTING AN ELECTRIC CIRCUITApplication filed July 12, 1928, Serial No. 292,173, and in GreatBritain July 21, 1927.

This invention relates to an apparatus for closing and interrupting anelectric circuit and more specially an apparatus for rectifying orcommutating an alternating voltage.

5 According to the general principles of the invention the apparatuscomprises a conductive liquid jet travelling at a constant velocity, atleast two electrodes adapted to be touched by the said jet and at leastone knife adapted 0 to cut the jet periodically in order to produce ajet chain with straight links which connect the said electrodessynchronously with the said alternating voltage.

The invention further comprises other features which will appear fromthefollowing detailed description.

Referring now to the accompanying drawings Figures 1-6 showdiagrammatically va- 0 riousforms of straight chain conductors,

Figures 7-1() show various forms of chain conductors produced by cuttinga liquid jet by one or more rotating knives,

Figures 11 and 12 illustrate methods of cutting a liquid jet by anoscillating knife,

Figures 13 and 14 illustrate a method of producing a jet chain of a etwave consisting of curved and straight parts, theA jet being shown intwo diiferent positions,

0 Figure 15 shows diagrammatically the pulsating current used forproducing the jet wave shown in the preceding figures,

Figures 16 and 17 showtwo embodiments of rotary jet chain rectifiers,

Figure 18 shows a commutator comprising two rectiiiers of the type shownin Figure 16, Figure 19 shows a. modiiication of the same', Figure 2()shows a commutator for a direct y@ current generator involving theprinciples of the invention, and

Figures 21 and 22 show two embodiments of commutators making use of anoscillating knife driven by a jet wave vibrator and a 5 moving coilvibrator respectively.

The general principles underlying the invention will first be more fullyexplained whereafter some of the practical uses of the apparatusaccording to the invention will be y0 described.

The chain conductor ln Figures 1-6 is shown an infinite electricalconductor C which has been divided into pieces or links. It is assumedthat the total device, the chain conductor, travels with. constantvelocity o along its own axis and that two electrodes E and E areconstantly touching the chain during its progress. Every time a cutcomes inside the space between the two electrodes the electricconnection between the same is interrupted. In Figure 1 in which thelinks are -of equal length )t there will occur one interruption duringthe time T which it takes for the chain to proceed one link. The saidtime, the period of the travelling chain, is thus determined by theexpression 1 =fvT.

The time during which E and E are connected, the time of connection, is

and the time of interruption is vas a being the distance between theelectrodes E so must be fulfilled. Under this supposition the followingwill be true:

Alternately the chain may have interspaces of greater length bo betweenthe links, Figure 3. Again b 7 and More complicated chain conductors maybe used for the closing and interruption of a circuit once in the periodT'. Thus Figure 4 shows a chain C with two gaps to the linklength. Achain like that in Figure 5 with )wa-tcl T=`v y c being the width of theelectrodes.

Jet 07min conductors A very simple way of producing a chain 'conductoris to apply a conductive liquid jet which is cut periodically by a knifeK, rotating in a plane perpendicular to the jet Figure 7. If a chain ofthe period T is desired for example, a knife which rotates once in thetime T may be used. In this way a chain of the type in Figure l isobtained. If it be desired to make the interval of connection equalaccording to 2, just the distance sired to be T 5 ga must be 6A and soon. It is possible to utilize the nozzle proper N as one electrode E,Figure v8. This actually amounts to the same as to fix the electrode Ein the point P, thus nearly in t-he plane of the knife K. In order togive the time of connection the right value it is suicient to adjust theelectrode E only, but of course the distance a may also be adjusted bymoving the knife K with regard to the electrode E.

A jet chain of the type shown in Figure 2 obtained by cutting the jet'bytwo knives 1 and K2. The knives may be arranged at the same distancefrom the jet as shown in Figure 9. The effect is, according to 50, that.

the distance a is reduced by the distance X1 between the two cuts. Bothof the knives K1 and K2 may with the same effect be pla-ced in the planeof rotation, Figure 10. If-their angular distance is 6, b will be If nowfor instance it is desired to make the interval of connection equal toIt may still be noted that the effect of the width A, F igure?, of thegap, which the knife makes in the jet, is to reduce a by A.

Jet chains of a given period T may be produced in several other waysthan by synchronously rotating the knife. Thus a symmetrical knife orwall with two edges oscillating or vibrating in a'l plane perpendicularto the jet with a period 2T may be used. Even a simple knife may be usedvibrating with a period T if the knife by some device is prevented fromcutting the jet during every second half-period of the vibrations. InFigure ll a solution of this problem is presented. The vibrating systemis marked with B,- B and has an arm C to which the knife K is attachedin'such a way that it is free to turn about a pivot 0 in one directionrelatively to the line of symmetry of the arm C while the motion in theopposite direction is limited by a stop Q. Furthermore the knife isfurnished with a damping device, for example a liquid damper formed by aplate D projecting into the liquid in a vessel T. Now, when the arm C isswinging from left to the right the stop Q will cause the knife K tofollow the arm thus cutting the jet J while, when the arm C is moved inthe opposite direction, the damping device will delay the motion of theknife K thereby lifting the same and preventing it from .hitting the jetJ.

Even with a knife vibrating once in the period T and cutting the jettwice in the said period, jet-chains suitable for closing an electriccircuit during periods between zero and T /Z may be produced. Figure 12indicates a device of this kind. The knife K is assumed to vibrateaccording to and to have its zero-position displaced rela.- tively tothe axis of the jet 'J by the distance y1. If a period of interruptionT/2 between E and E' is required this may be achieved by giving y1 anyvalue between 0.707 y0 and yo, corresponding to which a will assumevalues between )./4 and M2. Or if for instance it be desired to give theperiod of interruption the value 5/6 T, this can be accomplished bymaking y1=0259 y0 and a= 5/6 A/Q.. ()t='vT) etc.

A jet-chain of given period Tmay be produced from a jet-wave of the typeindicated in Figures 13 and 14. The wave in question consists of curvedand straight parts covering the same length and proceeding oneWave-length in the time T. It may be produced through the interactionbetween a constant field F and a pulsating current of the period T andof the type indicated in Figure 15. The bends of the wave hit a screen Uwhich pares them ofi leaving a jet-chain consisting of conductive partsa little longer than )t/Q--o T /2, v being the velocity of the jet wave.

Having now considered the various ways in which jet-chains of a givenperiod may be produced, afew applications of chains according to theinvention shall be indicated. The most important is undoubtedly that ofthe application of the jet chains for synchronous commutation orrectification of a given alternating voltage. The first condition forsuch rectification is that the period of the chain T :Mo coincides withthat of the alternating voltage. Moreover the rectification demands adefinite interval of connection say one half-period or one third or twothird of the half-period, and finally it requires that the interval ofconnection commences at a definite point of the period of thealternating voltage. The way in which these conditions are fulfilled invarious forms of synchronous jet-chain rectifiers and commutators willnow be considered.

Rotary g/pe jet-chain commutator and rectifier The jet .I is cut by theknife K rotating synchronously with the alternating voltage to becommutated, Figure 1G. In Figure 16, 40 designates the input terminalsof the apparatus. To the terminals 40 is connected the primary of atransformer 41, the secondary of which is connected in series with theelectrodes E and E and the o-utput terminals 4:2 of the apparatus. Theknife K is secured to Jthe shaft A of a synchronous motor 43 connectedto the terminals 40. It is at once achieved that the period of the chainagrees with that of the voltage. The appropriate interval ofinterruption is, according to what has been stated above, obtained byvarying the distance between the electrode E and the plane of rotationof the knife K. In order to have the interval commence at the rightpoint of the period of the alternating voltage it must, in the case ofFigure 16, either be possible to turn the knife K on the shaft A of thesynchronous motor 43 or to turn the stator of the latter relatively toits rotor. in the second form, Figure 17, the position of the electrodeE has not been fixed and consequently, it is possible to obtain theright moment of commutation by moving the pair of electrodes E and E asa unity. This property of the commutator in Figure 17, certainly meansan advantage. Another advantage is that the knife K is kept away fromthe commutation spark. In Figure 16 the latter appears at the knife Kwhich, therefore, must be made of a material with a melting-point above2000o C., preferably tungsten. In Figure 17 the yspark is formed betweenthe electrode E and the end of the chain link. Thus, instead of havingthe knife attacked the electrode is subject to the corroding effect ofthe spark.` It will be understood that in the case of Figure 16 thealternating current to be rectified is applied to the terminals 40. Thiscurrent also serves to drive the motor 43. The current in thetransformer secondary passes the electrodes E and E and the jet J whichcuts away the positive or negative half waves so that the currentderived at the terminals 42 will be a rectified current.

The shaft of the knife K is not bound to rotate just once in the periodof the alternating/voltage. It may, for instance, make one rotationduring two periods but then there must be two knives on the shaft withan angular distance of 180, in order that the jet may be cut once in theperiod.

A commutator in its simplest form making use of the rectifier indicatedabove is shown in Figure 18 and consists of two rectifiers, theelectrodes El and E2 of which may be connected to the terminals of thesecondary V1, V2 of a transformer, the primary 50 of which is connectedto the input terminals 51 of the commutator. The center C of thesecondary winding V1, V2 and the electrically interconnected electrodesE1 and E2 will then be the terminals to which the direct current wiresD2 and D1 should be connected. Obviously one rotating knife may be usedfor cutting both jets ,Il and J 2 provided the shaft A rotates once inthe period of the alternating current.

The shaft A is the shaft of a synchronous motor 52 connected to theterminals 51.

In this figure means are shown for causing the liquid jets J1 and J2 toemit from the electrodes El and E2, respectively. These electrodes areformed by nozzles at the lower end of vertical tubes 53 and 54projecting downwards from a reservoir 55 containing the liquid fromwhich the jets are formed. The liquid is fed to the reservoir 55.through a tube `56, and the reservoir is provided wlth an overflow tube57 so that the liquid in the reservoir wil be at a constant level. As aconsequence the velocity of the jets J1 and J2 will be constant. Ifdesired the tube 57 may be adjustable in the vertical direction so thatthe constant velocity of the jets can be altered.

In Figure 18 also `means are shown for altering the distance between theelectrodes E1 and El and the electrodes E2 and E2 respectively. Each ofthe electrodes El and E2 is carried by an insulator 58 secured to aslidev59 which can be adjusted in vertical direction in relation to afixed support 60 by means of a screw 61 which is screwed through abracket on the support and abuts against the slide 59. According to whathas been previously stated the distance between corresponding electrodesis adjusted in order to give the time of connection of the electrodes bythe links of the jet the right value.

In order that the moment of connection of corresponding electrodes mayalso be adjusted the stator of the motor 52 is arranged rotatably infixed bearings 62 co-axial with the shaft A, the adjustment beingperformed by means of a worm 63 intermeshing with a worm wheel 64rigidly secured to the stator. When the stator is turned the phase ofthe knife K is altered.

It should be noted that, as a rule, the jetchain J1 must not have brokenthe connection between the electrodes E1 and El before the jet J 2 hasestablished it between the electrodes E2 and E2. Thus for a shortinterval of time the transformer secondary V1, V2 will beshort-circuited through the jets. Now in order to keep the currentoriginating in this short-circuiting under control it is desirable tointroduce a resistance in the circuit during the commutation. This canbe effected in the manner indicated in Figure 19. A resistance r is hereinserted between the electrode El and a secondary electrode e', and thecurrent lis forced through this resistance in the timeinterval duringthe gap G moves from the electrode e to the electrode El.

Jet chains produced by a rotating knife are especially adaptable tocommutators in generators for direct current. Figure 20 indicates agenerator with a stationary armature S and rotating magnet system (notshown). The commutator bars are. 1, 2 6. Each bar is hit. by two jets,thus l by J1,1 and J 2,1, emitted from two reservoirs R1 and R2respectively mutually insulated and forming the terminals of themachine. Two knives K1 and K2 with an angular distance of 180o arefastened to the axis of the rotating magnet-system. The one knife willin turn cut all the jets JM, J1'2 JL@ and these jets only, the other inthe same manner the jets 2 1, J 2,2 J 2,6. Thus two sets of jet chainsare produced. In each set there is in the case considered, a phasedifference between two consecutive chains of 1/6 of the time ofrevolution. Furthermore the dimensions. have been so chosen, that eachjet-chain will only make connection between its reservoir and itscommutator-ba-r during l/6 of the time of revolution or generally alittle more. Obviously the effect of the jet-chain systems is just thesame as that of two rotating brushes. But the jet-chain commutator hasthe advantage that it may be made to stand commutation sparks ofconsiderable intensity. This means that sparking will practically nolonger put a limit to the power or voltage of a direct current generatoror motor. The difference between the ordinary direct current commutatorand the jet-chain type lies mainly in the fact that in the latter thecommutator bars can easily be insulated against each other and that thebars are not subject to any wear by a possible sparkformation, the sparkbeing displaced to the knife or to a non-wearing electrode between theknife and the bar.

Jet-cka-z'n-conwnu-tators and rectz'yiers 'with knife 'vibrating withthe period T of an alternating current From what has been stated aboveit appears that a jet-chain produced by cutting a jet by a knifeoscillating or vibrating with the period of an alternating voltage maybe used for the commutation or rectification of the said voltage. rlhereare different ways to make the knife vibrate synchronously with thevoltage. Two embodiments shall here be described which are especiallysuited for the purpose.

One is shown in Figure 21. Each of the jets J1 .or J2 are cut twice bythe knife K which vibrates synchronously with the alternating voltage.The vibrations are set up by the device shown above the rectifier. Itcan be termed a. jet-wave vibrator and consists of a jet-wave J1 hittingan oscillatory system B,

B the axis of which is marked with O. The

j et-wave is produced in the ordinary way by the interaction between aconstant magnet field F and an alternating current delivered by atransformer V2. j

The current must be synchronous with the alternating voltage to berectified. The bar B, B will of course vibrate synchronously with thesame voltage and obviously the phase-displacement.between its motion andthe voltage may be varied continuously by changing the distance betweenthe field F and the bar B, B. Thus a means for adjusting the rightmoment for the cutting of the jets J1 and J2 relatively to the voltageis available, and according to what has ben set forth above, the nozzlesNl and N2 of the jets J1 and J 2 may be used as electrodes. If theadjustment of the phase-displacement mentioned above is undertaken bymoving the bar B, B the whole rectifier must, of course follow thevibrator. Obviously the phase-displacement in question may also beinfluenced by altering in some way or other, for instance by aninduction regulator, the phase-dierence between the voltage of thetransformer Va and the voltage to be rectified. In the rectifier shownin Figure 22 the v1- bration of the fiat knife K is set up by a system,a so called moving coil vibrator, like that used in a moving coilammeter. An alternating current synchronous to the voltage to berectified is passed through the coil or frame D of the vibrator, thecoil or frame being arranged in a constant magnetic field between twomagnet poles N and S. If the nozzles 0f the jets J1 and J 2 are to beused as electrodes, the right moment for the cutting must be adjusted byinfluencing the phasediference between the current through the coil orframe D and the voltage to be rectified.

Obviously each of the two devices for producing the jet-chains inFigures 2l and 22, thus the jet-wave-vibrator and the moving coilvibrator, may also be used for the production of jet-chainswith one cutto the period. It is only sufficient to apply currents with doubleperiod 2T for the production of the et-wave J or for the feeding of themovin coil D.

aving thus fully described my invention I claim as new and desire tosecure by Letters Pat-ent:

l. An apparatus for rectifying an alternating voltage comprising meansfor producing a substantially straight jet of a conductive liquid andcausing the same to travel at a constant velocity, a knife, means foractuating the knife to cut the jet periodically to produce a jet chainwith straight links,

. and two electrodes, one of which is arranged behind the other in thedirection of motion ofthe jet, and which are positioned to makeelectrical contact with the jet chain, the distance between theelectrodes beingless than the length of the links of the jet chain.

2. An apparatus for rectifying an alternating voltage comprising anelectrode forming a nozzle, means for causing a substantially straightjet of a conductive liquid to issue from the nozzle at a constantvelocity, another electrode arranged in the path of the jet to makeelectrical contact therewith, a knife, and meansfor actuating the knifeto cut theA jet periodically at a point between the said nozzle and thesecond mentioned electrode to produce a jet chain with straight linksconnecting the nozzle and the electrode synchronously with saidalternating voltage.

3. An apparatus for rectifyin an alternating voltage comprising means orproducing a substantially straight jet of a conductive liquid andcausing the same to travel at a constant velocity, a knife, means foractuating the knife to cut the jet periodically to produce a jet chainwith straight links, and two electrodes one of which is arranged behindthe other in the direction of motion of the jet and which are positionedto make electrical contact with the jet chain, the electrodes beingmovable for altering their mutual distance to vary the period ofconnection of the electrodes by the links of the jet chain.

4. An apparatus for rectifying an alternating voltage comprising meansfor producing a substantially straight jet of a conductive liquid andcausing the same to travel at a constant velocity, a knife, means foractuating the knife to cut the jet periodically in order to produce ajet chain with straight links, two electrodes one of which is arrangedbehind the other in the direction of motion of the jet and which arepositioned to make electrical contact with the jet, means for alteringthe distance between the electrodes to change the period of connectionof the electrodes by the links of the jet chain, and means for alteringthe moment of cutting of the jet by the knife for changing the moment ofconnection of the electrodes.

5. An apparatus for rectifying an alternating voltage comprising meansfor producing a substantially straight jet of a conductive vliquid andcausing the same to travel at a constant velocity, a knife, means foractuating the knife to rotate synchronously with the said alternatingvoltage and to cut the said jet to produce a jet chain with straightlinks, and two electrodes one of which is arranged behind the other inthe direction of motion of the jet and which are positioned to makeelectrical contact with the links of the jet chain, the distance betweenthe electrodes being less than the length of the links of the jet chain.

6. An apparatus for rectifying an alternating voltage comprising meansfor producing a substantially straight jet of a conductive 'liquid andcausing the same to travel at a constant velocity, a knife, means foractuating the knife to rotate synchronously with the said alternatingvoltage once-in the period of the same and to cut the jet to produce ajet chain with straight links, and two electrodes one of which isarranged behind the other in the direction of motion of the jet andwhich are positioned to make electrical contact with the links of thejet, the distance between the electrodes being less than the length ofthe links of the jet chain.

In testimony whereof I have aiiixed my signature.

JULIUS FREDERIK GEORG POUL HARTMANN.

